Effect of unilateral superior cervical ganglionectomy on mandibular incisor eruption rate in rats

To assess the effect of sympathectomy on rat tooth eruption, the effect of a unilateral superior cervical ganglionectomy (SCGx) on eruption rate of ipsi- and contralateral lower incisors was examined. Two experiments were performed. In a first experiment, the eruption rate of ipsilaterally denervated incisors was similar to that of contralaterally innervated incisors, when assessed for up to 28 days after surgery. In a second experiment, under conditions of unilateral unimpeded eruption of incisors performed ipsilaterally or contralaterally to a unilateral SCGx, a significantly lower eruption rate of denervated incisors at the impeded eruption side, and a significantly higher eruption rate of denervated incisors at the unimpeded side were observed, when computed every 2 days. Significant differences in individual Student's t tests at every time interval occurred mainly during the first and the last week of examination. When average daily eruption rate was computed in weekly intervals, a significant interaction between SCGx and the side of impeded or unimpeded eruption was found in a factorial ANOVA, that is, for each of the 4 weeks of examination, sympathetically denervated incisors showed lower eruption rates at the impeded eruption side, and higher eruption rates at the unimpeded side. These results indicate that incisor eruption is not modified by a local sympathetic denervation unless the contralateral lower rat incisor is cut out of occlusion.

Effect of experimental diabetes on mandible growth in rats

The aim of the present work was to assess the effects of experimental diabetes on mandible growth in rats. Experimental diabetes was induced in rats, aged 26 d, by a single dose of 100 mg/kg b.w. of Streptozotocin (STZ). Thirty-one d post STZ or vehicle injection, the animals were killed. Mandibles were resected to determine Mandibular Skeletal Units dimensions (MSU) and overall mandible growth. Statistical analysis of results revealed, for STZ treated animals as compared to the control group: 1) a decrease in b.w.; 2) an increase in food intake; 3) an increase in glucemia (200%); 4) normal hemoglobin, creatinine and plasma urea values; 5) a reduction in growth of symphyseal (9%), coronoid (16%), and alveolar (13%) heights, condyloid (11%), angular (8%), and base (3%) lengths, and condyloid width (8%). Mandibular length (4%), height (8%) and length of base (6%) were significantly lower in diabetic animals as compared to the control group. No significant differences in length of symphyseal process, alveolar length and height of base were found between groups. Rats on a restricted diet, resulting in a decreased b.w., and the control group exhibited similar mandibular dimensions. These data show that STZ-induced diabetes reduces mandibular growth, resulting in some deformity of the structure.